Compositions comprising oil-in-water or water-in-oil microemulsions are well known for providing cleaning concentrates which, upon dilution with water, form cleaning formulations having a delivery strength that is easily adjustable by the user. However, the "oil" phase of such microemulsions has consistently been described as, for example, a natural oil, a petroleum distillate (mineral spirit or hydrocarbon), a sparingly soluble organic solvent, or a perfume or fragrance oil, all of which may be categorized as lipophilic oils or solvents. Examples of these microemulsions include the series of patents to Loth et al., U.S. Pat. Nos. 5,075,026, 5,076,954, 5,082,584 and 5,108,643 (perfume); to VanEenam, U.S. Pat. Nos. 5,080,822, 5,080,831, 5,158,710 and 5,419,848 (sparingly soluble organic solvent); to Rosano, U.S. Pat. Nos. 4,146,499 and 4,472,291 (hydrophobic/lipophilic oil or solvent); to Mihelic et al., U.S. Pat. Nos. 5,401,325 and 5,401,326 ((lipophilic) organic solvent); and the single patents to Erilli et al., U.S. Pat. No. 5,393,468 (water insoluble organic compound) and Spaulding et al., U.S. Pat. No. 4,867,898 (pine oil).
Microemulsions of certain compositions may, upon dilution, transform from a clear solution to a solution having a milky color or appearance, as opposed to retention of a clear solution (which may or may not still remain as a microemulsion) or the formation of a mixture having two or more separated phases. This phenomenon is termed in the art as a "bloom" or "blooming. " Such a bloom is most commonly the result of formation of a macroemulsion, but, as will be seen later herein, it may also be due to formation of a dispersed liquid crystalline state. In addition to imparting an aesthetic appearance, the blooming feature signals the user that an appropriate concentration or strength has been attained that is useful for most cleaning applications.
Well known blooming microemulsion compositions are those which, as with the general category of dilutable microemulsions described above, contain a lipophilic oil, in particular pine oil, which is primarily composed of terpenes. Such a lipophilic oil, at least heretofore, has been a necessary constituent to any formulation that is capable of blooming. However, pine oil, for example, imparts at least some underlying pine scent to any composition in which it is employed, thereby limiting the variety of scents or fragrances one might wish a cleaning composition to have.
Described in U.S. Pat. No. 5,591,708, issued to Richter in 1997, is a composition for which it is the stated goal to develop a pine oil type cleaning composition in which the amount of pine oil present in the product is reduced, but which still exhibits one or more of the (favorable) identifying characteristics of pine oil, including a pine scent and a blooming capability, of which the latter is clearly most important for purposes of that patent. Called out as essential elements (in addition to water) for the Richter composition are pine oil (referred to in the patent as "constituent A"), a nonionic surfactant exhibiting a cloud point of 20 C or less ("constituent B"), and a solubilizing agent which may include lower alkyl alcohols and lower alkylene glycols ("constituent C"). Optional constituents include, among others, a nonionic surfactant exhibiting a cloud point of greater than 20 C, and a cationic surfactant in the nature of a germicidal quaternary ammonium compound.
There is no suggestion in Richter that the pine oil constituent might be eliminated entirely and there still be achieved a cleaning composition that is capable of blooming. Indeed, Applicants' own experiments reveal that when the pine oil is removed from a composition otherwise identical to the preferred "E1" formulation given in Richter, the resulting composition does not bloom when diluted with water.
Described in U.S. Pat. No. 5,035,826, issued to Durbut et al. in 1991, is a microemulsion cleaning composition which forms a liquid crystal when diluted with water in an amount not exceeding three parts of water per part of the concentrated composition. While this reference never speaks of a composition which "blooms" per se, one form of the liquid crystal state which occurs upon dilution is variously described in the patent as being "cloudy or milky" or "turbid or lactescent." This would possibly suggest that a bloom may be occurring when the composition of that reference is diluted.
The necessary constituents (in addition to water) of the Durbut invention are a mixture of nonionic and ionic surfactants, a cosurfactant which is preferably a monoalkyl ether of a lower glycol or polyalkylene glycol, and a lipophilic organic solvent which is preferably a hydrocarbon. The nonionic surfactant component is most preferably a mixture of a larger amount of a nonionic surfactant which is more hydrophilic, and a smaller amount of a nonionic surfactant which is less hydrophilic. The ionic surfactant component may be either anionic or cationic, the latter including quaternary ammonium compounds.
Again, there is no teaching, disclosure or suggestion in Durbut that the lipophilic solvent should be eliminated entirely and there be achieved a cleaning composition that is still capable of blooming. Indeed, the phase diagrams depicted in that patent indicate that when the composition of that patent has zero paraffin (i.e., zero lipophile), there is no liquid crystal formation, and thus presumably no bloom.
The compositions of Richter and Durbut are both but further examples of microemulsion compositions of the type in which a conventional lipophilic oil or solvent is employed for the oil phase.
Thus, there is believed to be no prior art which teaches, discloses or suggests that one can form a cleaning concentrate comprising an oil-in-water type of microemulsion without a conventional lipophilic oil or solvent also being present. It follows from the foregoing that it is also believed that there is no prior art which teaches, discloses or suggests that one can form a microemulsion concentrate capable of blooming upon dilution with water without a conventional lipophilic oil or solvent also being present.